In the midst of big budget tales about robots and apes, a languid movie about growing up made a splash of its own this weekend.

“Boyhood,” director Richard Linklater’s critically acclaimed, naturalistic movie shot over 12 years with the same characters playing a young man, his sister and parents as they all age, opened to $387,618 in five theaters. Its per theater average of $77,524 was very strong and the second highest of 2014, behind only the opening of Wes Anderson’s “Grand Budapest Hotel.”

Particularly impressive is that the movie came from tiny IFC Films, typically known for releasing movies in theaters at the same time as video-on-demand, which was not the case with “Boyhood.” Advertised primarily in newspapers and online, “Boyhood,” which stars Ethan Hawke and Patricia Arquette, appeared to succeed thanks to rave reviews and buzz among cineastes that has been building since Mr. Linklater first showed the nearly 3-hour movie at the Sundance Film Festival in January.

Some movies that start off strong in a few theaters in New York and Los Angeles become major hits, like “Grand Budapest Hotel,” which has grossed nearly $60 million.

But others have trouble finding a broader audience. “Inside Llewyn Davis,” which had an opening per-theater average of $101,353, ended up with just over $13 million. Woody Allen’s “Melinda and Melinda” grossed $74,238 from one theater on its first weekend but finished its run with $3.8 million.

IFC has an ambitious plan to open the movie in dozens more theaters all the way through August, starting with 18 more theaters in 13 cities next weekend, including Chicago, Boston, San Francisco, and Mr. Linklater’s home town of Austin, according to the “Boyhood” website. But it remains to be seen whether a conflict-free movie that’s essentially about nothing more – or less – than an average life can find its own, broader audience in the coming weeks against the openings of “Hercules,” “Guardians of the Galaxy,” and “Teenage Mutant Ninja Turtles.”